Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
This is how i've been playing Sion, it has worked very damn good the latest 400 games. I don't think there is any better build then this for Sion as DPS. If you know any improvements then tell me.
The runes. I took the defence runes to be abÃ¶e to stand longer in the lane and less dmg in fights. The attack speed is just so good, kinda the only thing he needs.
Masteries. I think thats a pretty good way to spec, the dodgeis good when you should run towards someone or away form someone. And the dodge also makes you good against other melee champs and mobs.
Skills. Always level up Enrage as soon as possible so you get more Hp for atmas. The stun only need 1 spec in beggining, doesn't do any important damage. The Shiled is to absorb damage when you jungle and very good to harass.
Items. Why i took this items is becasue I've tried many many builds. And this one worked best! Phantom dancer makes you faster and better attack speed, and dodge. Some of the most important grounds for Sion. Then after take bloodthirster because it stacks and really owns if you kill much mobs. Then as the 4th item I take atmas because at that time i should have probebly like 2500HP wich gives pretty much damage. REally awsome. Then I take the black cleaver so I can kill champs with much armor more esier and it gives pretty good DMG also. And the infity egde is really good to, you can decide wich one you take first, but I always take the black cleaver.
I'm sorry about my English, I'm in a hurry, I'll update it later.